Property, Plant and Equipment, Net (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Utility plant in-service:
Common general	$ 234	$ 212
Utility plant in-service	3,812	3,764
Accumulated depreciation and amortization	(1,300)	(1,301)
Utility plant in-service, net	2,512	2,463
Construction work-in-progress	128	89
Property, plant and equipment, net	2,640	2,552
Average depreciation and amortization rate	3.00%	3.00%	2.90%
Asset impairment charge	12us-gaap_AssetImpairmentCharges	4us-gaap_AssetImpairmentCharges
Asset Impairment Charges, 2014 PUCN Companion Filing General Rate Case	8
Electric Plant [Member]
Utility plant in-service:
Generation	1,036	1,070
Distribution	1,321	1,289
Transmission	719	685
Intangible plant	123	138
Gas Plant [Member]
Utility plant in-service:
Distribution	366	357
Intangible plant	$ 13	$ 13

Asset Impairment Charges, 2014 PUCN Companion Filing General Rate Case

No definition available.

Name:	sppc_AssetImpairmentCharges2014PUCNCompanionFilingGeneralRateCase
Namespace Prefix:	sppc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Public Utilities, Property, Plant and Equipment, Net, Excluding Construction Work In Progress

+ References

No definition available.

+ Details

Name:	sppc_PublicUtilitiesPropertyPlantandEquipmentNetExcludingConstructionWorkInProgress
Namespace Prefix:	sppc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Public Utilities, Property, Plant and Equipment, Plant in Service, Excluding Construction Work In Progress

+ References

No definition available.

+ Details

Name:	sppc_PublicUtilitiesPropertyPlantandEquipmentPlantinServiceExcludingConstructionWorkInProgress
Namespace Prefix:	sppc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2420-110228

+ Details

Name:	us-gaap_AssetImpairmentCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period end book value of accumulated depreciation on property, plant and equipment (PPE) that is owned by the regulated operations of the public utility.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Period end amount of property, plant and equipment (PPE) related to regulated assets common to business units.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentCommon
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Period end amount of construction work in progress in public utility.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Composite depreciation rate for public utility plants in service.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period end amount of property, plant and equipment (PPE) related to utility distribution.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDistribution
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Period end amount of property, plant and equipment (PPE) related to generation or processing owned by public utility.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Period end amount of total net PPE.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Period end book value of other property, plant and equipment (PPE) owned (but not classified elsewhere) by the public utility.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period end amount of property, plant and equipment (PPE) related to utility transmission owned by public utility.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentTransmission
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_PublicUtilityAxis=us-gaap_ElectricityGenerationPlantNonNuclearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilityAxis=us-gaap_NaturalGasProcessingPlantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: